1. Field of the Invention
The invention relates to storage-stable compositions of organosilicon compounds which contain amino-functional compounds, and to a process for stabilizing organosilicon compounds.
2. Background Art
Organosilicon compounds such as compositions based on silanes and organosilanes, polysiloxanes and organopolysiloxanes are employed in many fields, for example as adhesion promoters, crosslinkers in polymers, as release agents, as additives in paints and coatings, for the hydrophobicization of surfaces, including those of textiles and leather, and especially for the protection of buildings and facades, for book preservation, for the special modification of the properties of surfaces such as the coating of glass fibers or the silanization of fillers and pigments, and also for the improvement of the rheological properties of polymer dispersions and emulsions.
For the preparation of silanes and/or organosilanes which have hydroxyl and/or hydrocarboxy groups such as alkoxy groups bonded to silicon atoms, halosilanes, especially chlorosilanes, are generally used. The reaction of a halosilane with an alcohol to obtain an alkoxysilane is known per se to those skilled in the art and is also referred to as “esterification”. Hydrolysis of halosilanes, partial alkoxylates thereof and/or alkoxysilanes thereof in aqueous, acidic medium generates polysiloxanes or organopolysiloxanes. In the reaction of trihalosilanes with alcohol, the equilibrium constants decrease from the first to the third stage. This means that a third alkoxy group is particularly difficult to introduce, or that the introduced third alkoxy group reacts readily with hydrogen halide to reform a halosilane and/or halosiloxane structure. The latter are reactive and condense in the course of workup or of storage, whether neat, or a solution or as an emulsion. Even after destillative purification of the product, residual halogen contents, i.e. residues of acidic or hydrolyzable halide, remain in the silanes, organosilanes, polysiloxanes or organopolysiloxanes. This halide, Si-Hal, reacts with functionalities such as silanol groups Si—OH, atmospheric moisture, and residual traces of water or alcohol during storage to produce hydrogen halide which, as a condensation catalyst, can lead to an increase in viscosity of the silanes or polysiloxanes, including in some cases, gelling of the polysiloxanes.
Furthermore, condensation steps in the case of silanes and organosiloxanes which have hydroxyl and/or alkoxy groups bonded to silicon atoms release water and/or alcohol. With alkoxysilanes, traces of water lead to undesired formation of siloxanes. This increases the undesired VOC fraction of the free alcohol.
At present, there are efforts to prepare organosilicon compounds and products which comprise organosilicon compounds, and also compositions based on organosilicon compounds, with very low halide contents. In particular, commercial products are desired which have a very low halide content.
GB 594154 describes the stabilization of organosiloxanes against the action of heat and oxygen with the aid of from 0.05 to 5% by weight of an organic amine. Such large amounts of amine have the effect of shortening the storage stability of hydroxyl- and/or hydrocarboxy-containing organosiloxanes, since they promote gelling thereof at room temperature.
EP 197540 A describes the stabilization of linear organosiloxane oils and thiofunctional organosiloxanes against the action of heat and, where appropriate, kaolin, by addition of an organic amine.